Calling the Silk Road "essential" might seem an exaggeration,
but it won't be if you're one of its many regular users. Nor if
you're a regular user of Bitcoin -- its journey to mainstream
acceptance began with the Silk Road, being as it is perfect for
anonymous, untraceable transactions (as long as you're careful not
to make your identity obvious, of course).

Right now, Bitcoin is undeniably a mainstream currency, even if
it is not necessarily popular in the sense of being used by a
significant proportion of society. That is, it is viewed as a
legitimate method of payment, and a legitimate asset, by the people
who matter in these issues -- CNBC has it as a ticker on
its website, for example, and there's a Bitcoin hedge fund in Malta.

That isn't to say it doesn't have issues, though. The Bitcoin bubble was a fascinating game of musical chairs
played out over several months -- everyone knew the music would
stop, but nobody wanted to guess when that might be while there was
easy money to be made. Also, DDoS attacks have been incredibly
effective at manipulating Bitcoin's value. Closing a large exchange like Mt Gox, even if only for a few
hours at a time, could cause enough of a price fluctuation for
canny hackers to buy low and sell high at their own whim.

For all Bitcoin's problems, the underlying concept is an
attractive one -- a cryptographically secure and anonymous currency
that doesn't take a cut from transactions.

For all
the Bitcoin hype, it's not hard to see that there's a big problem
in how bitcoins are actually used. That comes from Bitcoin being
both a currency and a commodity in its current guise. Its rise in
value has been the thing to make it famous, but that's also the
thing that has undermined its usefulness as a currency. But if
you're someone who wants to accept bitcoins as part of a business,
then having to update your prices every minute isn't necessarily
useful -- nor is the worry that deflation might discourage coins
from circulating, or the worry that the whole thing could pop
without warning.

Businesses have started accepting Bitcoin, to their credit.
There's a whole neighbourhood in Berlin that's seemingly converted
on mass, while the range of online services that accept it --
from Wordpress to
OK Cupid -- is now long enough to be essentially pointless
in listing, again significant in showing Bitcoin is now a
legitimate currency.

We may be entering a new period in how we pay for things online,
with Bitcoin as the first example of theory put into practice. Like
many new and radical ideas, its implementation has been sketchy,
inconsistent, with naysayers decrying it as a scam or a Ponzi
scheme, its acolytes proclaiming it a crucial weapon in the
liberation of the individual from the corporatist banking system
and government regulation of commerce.

This argument sees Bitcoin as to currencies/online markets as
Napster was to music piracy. The popularity of Bitcoin might well
have put the whole system under an immense amount of stress but the
underlying concept is an attractive one -- a cryptographically
secure and anonymous currency that doesn't take a cut from
transactions (like, say, Amazon's virtual currency), and which remains independent of
any single, central authority.

For many people, the risks -- from fraud, for instance -- are
outweighed by the benefits. So let's say you're not convinced by
Bitcoin as it is, but you still like Satoshi Nakomoto's idea
("an electronic payment system based on cryptographic proof instead
of trust, allowing any two willing parties to transact directly
with each other without the need for a trusted third party") then
there are other alternatives out there. Here are some of the more
interesting ones, all forked from the original Bitcoin code.